Fabrication of a structural workpiece (such as, for example, a structural steel I-beam, wide flange beam, angle, channel, flat plate, etc.) may require cutting, drilling, punching, and severing portions of the workpiece. Conventional machines perform these processing operations. For example, a machine can be used to drill holes in a workpiece (e.g., a structural beam).
In one type of machine, a workpiece, such as a structural beam, is supported lengthwise on, and clamped to, a table adjacent a drill carriage which supports a drill spindle so that a drill mounted thereto can be moved to desired locations along the length of the beam, along the height of the beam, and toward or away from the beam.
In some machines, the drill spindle can also be tilted (angled) in a plane that is perpendicular to the length of the beam support table and/or can be tilted (angled) in a plane that is parallel to the horizontal support surface of the beam support table.
In another type of machine, the beam or other workpiece is moved through an assembly of tools (e.g., punches, drills, etc.) which are at fixed locations along the length of the machine.
Structural beams may have to be provided in appropriate lengths for being erected in specific structures. Methods for creating one or more shorter segments or beams from a length of stock include severing the shorter segments from the length of stock with a cutting torch or with a shearing apparatus.
When beams are erected in structures, the ends of the beams and/or other portions of the beams are typically connected together with bolts. The bolts are received in holes provided in the webs and flanges of the beams.
Conventional methods for providing the bolt holes in a beam include drilling the holes with one or more drill spindles, or punching the holes with one or more punch presses. For example, “web” punch presses may be used to provide holes in the beam web, and “flange” punch presses may be used to provide holes in the beam flanges. Such punch presses may have conventional designs well-known to those skilled in the art. Various designs are disclosed in U.S. Pat. Nos. 4,631,996, 3,722,337, and 3,720,125.
Other systems for processing a beam or other workpiece may include apparatus having cutting torches for cutting the workpiece to length or cutting a profile in the workpiece. Various processes may be combined in one machine, or in one processing line having a number of different machines.
There is typically a need, at some point in the process (usually at an initial stage of the process), to determine the location of the workpiece relative to the process line or path (i.e., relative to the various tools that cut, shear, punch, drill, or otherwise operate on the workpiece at the desired locations along the workpiece). Typically, a leading end edge of a workpiece is determined (i.e., established or located) relative to a predetermined position of the operating tool or tools and/or relative to a fixed portion of the process line or machine in the process line so that subsequent processing operations can be programmed and/or performed relative to the initial location data of the leading end edge of the workpiece. In some processes, the trailing end edge of a workpiece may instead, or subsequently, be located (i.e., determined relative to the operating tools). In some other processes, a lateral edge or edges of a workpiece must be located.
In a typical workpiece processing apparatus or processing line, the ambient environment or atmosphere may be relatively dirty as a result of sloughing of rust or scale from the workpiece and/or as a result of the production of the chips and smoke from drilling and/or cutting operations. In addition, the ambient atmosphere can typically include spray mist coolant from coolant liquids that are used during drilling or cutting operations. The relatively dirty ambient atmosphere around the workpiece must be accommodated by any system employed for determining or locating an edge of a workpiece.
Mechanical systems for detecting the edge of a workpiece have been used in the past and continue to be used today. Such mechanical systems do not need to “see” through the dirty ambient atmosphere that envelopes the workpiece, but such mechanical systems are nevertheless subject to the effects of particulates, gases, and liquid materials that are present in the environment around the workpiece and that may over time foul operating components.
A typical mechanical system for locating an edge of a workpiece includes a spring-loaded mechanical switch that physically engages the workpiece. However, this subjects the switch component or components to physical wear and to potential physical damage. Such a mechanical system also requires a significant amount of room (typically for accommodating a support arm, springs, electronic switches to sense motion, etc.). Such a mechanical system thus typically needs to be offset from the operating tool (e.g., drill, cutting torch, etc.). This may require the machine to be longer and/or to require the workpiece or tool to undergo extra travel.
Some of the above-discussed disadvantages of a mechanical system for locating the edge of a workpiece can be eliminated or minimized by using an optical system employing a light beam directed transversely into the processing path of the workpiece so that the beam is perpendicular to the length of the workpiece and parallel to the width direction of the workpiece. When the light beam is interrupted by the leading edge of the workpiece, the light beam is reflected by the surface of the workpiece back to a photoelectric cell switch near the light source. This actuates the switch for indicating the location of the workpiece leading edge. In such a system, the light emitting source must be very near the workpiece path because smoke, mist, and chips can interfere with the transmission of the light beam that is directed at, and reflected from, the workpiece. Further, color and/or texture changes in the workpiece materials, along with changes in the distance between the workpiece and the switch, can cause problems in actuating the switch with the reflected light beam. Such a reflected light beam type of switching system may thus be somewhat inaccurate and/or unreliable.
It would be desirable to provide an improved system for locating an edge of a workpiece wherein the above-discussed problems could be eliminated, or at least substantially minimized.
It would be especially beneficial if such an improved system could operate effectively to locate the edge of a workpiece in an environment that is dirty, and wherein drill chips and spray mist coolant might be thrown or dispersed around the workpiece.
Such an improved system should preferably eliminate or minimize the likelihood of the workpiece or other objects in the environment from physically impacting or engaging the edge locator system in a way that could have a deleterious effect on the system.
It would also be desirable if such an improved system could be readily operated by an appropriate control system, could accommodate a variety of different types of workpieces (e.g., flat plates, channels, angles, beams, etc.), could produce accurate and repeatable results, and could relatively easily accommodate changes in the types and sizes of the workpieces being processed.
Also, it would be beneficial if such an improved system could employ components that are relatively small and that are relatively easy to fit in an existing processing machine or line.
Further, it would be advantageous if the improved system could be manufactured, installed, and operated without incurring excessive costs or expenses.